// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Diagnostics.CodeAnalysis;
using System.Formats.Asn1;
using Internal.Cryptography;

namespace System.Security.Cryptography.Pkcs
{
#if BUILDING_PKCS
    public
#else
    #pragma warning disable CA1510, CA1512
    internal
#endif
    sealed class Pkcs9LocalKeyId : Pkcs9AttributeObject
    {
        private byte[]? _lazyKeyId;

        public Pkcs9LocalKeyId() :
            base(Oids.LocalKeyIdOid.CopyOid())
        {
        }

        public Pkcs9LocalKeyId(byte[] keyId)
            // The ReadOnlySpan constructor permits null
            : this(new ReadOnlySpan<byte>(keyId))
        {
        }

        public Pkcs9LocalKeyId(ReadOnlySpan<byte> keyId)
            : this()
        {
            AsnWriter writer = new AsnWriter(AsnEncodingRules.DER);
            writer.WriteOctetString(keyId);
            RawData = writer.Encode();
        }

        public ReadOnlyMemory<byte> KeyId =>
            _lazyKeyId ??= Decode(RawData);

        public override void CopyFrom(AsnEncodedData asnEncodedData)
        {
            base.CopyFrom(asnEncodedData);
            _lazyKeyId = null;
        }

        [return: NotNullIfNotNull(nameof(rawData))]
        private static byte[]? Decode(byte[]? rawData)
        {
            if (rawData == null)
            {
                return null;
            }

            return PkcsHelpers.DecodeOctetString(rawData);
        }
    }
}
